Third Quarter 2011
Figure 3. Mixed ornamental and turfgrass plots at Gulf Coast Research and Education Center, Hillsborough County, Florida.
well as non-irrigated control plots. Irrigation water use was continually monitored and turfgrass quality ratings were taken at least every two months. Both 2004 and 2005 were above normal rainfall years. Averaged across all irrigation frequen- cies and brands, SMS control reduced water application 72% compared to time-based irrigation without a rain sensor (Cardenas-Lailhacar et al., 2008). The time-based irrigation schedule without a rain sensor actually applied less water than we have observed in residential irrigation systems in Central Florida (Haley et al., 2007), thus potential savings on homes may be even greater. SMS brands did not function identically, but three of the four tested were similarly effective with irriga- tion savings ranging from 70% to 90%. More recent testing results during the dry years of 2006 and 2007 has resulted in 34% savings compared to a schedule similar to many home- owners. Turf quality was not impacted by irrigation savings due to the wet conditions throughout 2004 and 2005. The SMS controllers had acceptable turf quality during dry years but non-irrigated plots had poor quality. We have also shown that SMS controllers can result in water savings as high as 53% on St. Augustinegrass during drought conditions while maintaining acceptable turf quality (McCready et al., 2009). In 2005, an ET controller test site was established at the
Gulf Coast Research and Education Center in Hillsborough County. The site was installed and plants established through- out the spring of 2005. This site consisted of twenty 1,000 sq. ft. plots that were 65% Floratam St. Augustinegrass and 35% mixed ornamental (Fig. 3). Three brands of ET controllers were tested along with two time-based comparison treatments. Over the testing period, which exceeded 15 months in 2006-
2007, ET controller savings across all brands averaged 43% compared to the timer irrigation control (Davis et al., 2009). Maximum savings were observed in the winter as ET control- lers effectively reduced irrigation based on weather conditions. As in the SMS studies discussed previously, irrigation savings did not result in significant differences in turfgrass quality. A 26 month study has just been completed where 59 cooperating homes in Pinellas County, Florida were divided into four groups and where different irrigation control strategies were employed as follows: 1) new SMS controller installed, 2) rain sensor installed and homeowner provided customized materials detailing timer setting throughout seasonal changes, 3) rain sensor installed, 4) no new control strategy in addition to existing irrigation timer. Over the study period, only the SMS strategy resulted in significant irrigation reduction of 65% relative to the group with just the timers for irrigation control as is typical for landscapes (Haley and Dukes, 2011). In summary, research on these control technologies has
shown the potential to reduce wasted irrigation water substan- tially. However, anecdotal evidence from implementation of smart controllers indicates lower savings when implemented on actual landscapes. Many initial installations suffered from poor installation and set up or a smart controller on a site with relatively modest pre-existing irrigation use trends. Future work will include optimizing set points for SMS thresholds, detailed programming instructions for all controllers under Florida conditions, comparing controller performance to estimated irrigation water requirements, and demonstration and testing of SWAT technologies at a large scale. Detailed (Continued on page 19)
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